Essential Production Implications

Maintaining the necessary correct fly ash moisture levels has become a critical component during processing. The MoistTech sensor will monitor the fly ash process in both wet and dry applications to reduce dust and provide dryer control.

As a barrier or fill material, fly ash is used as a substitute for natural soils. Fly ash in this application must be stockpiled and conditioned to its optimum moisture content to ensure that the material is not too dry and dusty or too wet and unmanageable. When fly ash is at or near its optimum moisture content, it can be compacted to its maximum density and will perform equivalently to well-compacted soil.

The water content of the fly ash stabilized soil mixture affects the strength. The maximum strength realized in soil-fly ash mixtures generally occurs at moisture contents below optimum moisture content for density. For silt and clay soils the optimum moisture content for strength is generally four to eight percent below optimum for maximum density. For granular soils, the optimum moisture content for maximum strength is generally one to three percent below optimum moisture for density. Therefore, moisture content must be controlled during construction.

Are You Measuring Moisture?

In the presence of moisture, fly ash reacts with lime at ordinary temperature and forms a compound possessing cement like properties. After reactions between lime and fly ash, calcium silicate hydrates are produced which are responsible for the high strength of the compound.

Conditioned: In this method, water is added to the fly ash to facilitate compaction and handling. The amount of water added being determined by the end use of the fly ash. Conditioned fly ash is widely used in aerated concrete blocks, grout and specialist fill applications.

The MoistTech staff is very experienced with the requirements in the production of fly ash. Our sensor calibrations, measurement wavelengths, algorithms and sensor optical requirements are pre-set at the factory. Typical accuracy is about ±0.1% moisture. Typical analog range is 0-10% moisture and up to as much as 40%, subject to application. The outputs can be adjusted to optimize PLC or recording requirements.